Swage fasteners, rivets, and similar fasteners are commonly used to secure together a wide variety of workpieces in industries ranging from aircraft and aerospace manufacturing to building construction. Such fasteners, which include a deformable head disposed around a shaft and a pintail which is detachably secured to the shaft, are collectively referred to herein as "pintail fasteners." As used herein, "head" is not restricted to a structure fixed to one end of a fastener. In some fasteners the head is secured about one end of the shaft. But in others the head includes a deformable collar which can be moved along the shaft before the fastener is installed by swaging the collar into locking grooves on the shaft.
Pintail fasteners are favored because they provide a tight, durable connection without threads, and because they may be installed rapidly. Pintail fasteners are often used to fasten materials such as sheet metal which are not amenable to other fasteners such as adhesives, nails, or screws.
Although pintail fasteners have numerous advantages, conventional installation tools used to install pintail fasteners suffer from several drawbacks. To understand the shortcomings of conventional installation tools, it is helpful to understand how a pintail fastener is installed. Initially, the pintail of the fastener is inserted between the jaws of a nose assembly which is attached to the installation tool. The nose assembly is typically detachable from the tool, so that one tool may be used with a variety of nose assemblies. The nose assembly is selected according to the particular type of fastener being installed.
At least a portion of the fastener's shaft is then inserted through aligned holes in the workpieces which are being fastened. The fastener is selected so that at least part of the fastener's head is larger than a hole in one of the workpieces. The head abuts the workpiece around the hole.
Next, an installation force is applied to the fastener by the installation tool and the nose assembly. The installation force is generated by the tool and is transferred to the nose assembly by a nose piston in the tool. The force is directed generally along the shaft and away from the workpieces. The nose assembly's jaws tighten around the pintail and urge the pintail, and hence the shaft, away from the workpieces. The pintail typically contains annular grooves to enhance the gripping ability of the jaws. The pintail grooves are normally separate rather than being formed as threads.
The installation force presses the fastener's head against the workpiece. The fastener is configured such that as application of the installation force continues, the head deforms in shape and the shaft moves further through the holes. Deformation typically increases the cross-sectional diameter of the head transverse to the shaft, and may also serve to secure the head so that it is immobile with respect to the shaft. Installation deforms the head in such a way that the workpieces are trapped between portions of the fastener which are larger than the holes.
The fastener is typically formed such that a portion of the shaft immediately adjacent the pintail is narrowed or weakened with respect to the rest of the shaft. Upon sufficient application of the installation force, the pintail therefore detaches suddenly from the shafts. The detached pintail may be discarded, or it may be collected for later use in forming new pintail fasteners.
Unfortunately, some conventional installation tools do not deal effectively with detached pintails. Depending on the circumstances, detached pintails may remain in place, or they may shoot away from the workpieces. The pressures required to properly deform fastener heads during installation commonly exceed three thousand p.s.i., so it is not uncommon for a detached pintail to fly rapidly away from the fastener shaft. Many conventional tools simply deflect the flying pintails toward the floor to prevent injury to the tool's user or other damage.
Such conventional tools thus permit the detached pintails to lie haphazardly about the work area. Because the detached pintails must eventually be collected in any case when the work area is cleaned, some known tools include a pintail container which holds ejected pintails. One such container consists of an inner bottle and an outer bottle which are rotatable relative to one another. Each of the bottles has a slot in its side. The bottles are configured such that a pintail may be removed from within the container by rotating the bottles until the slots align and then aligning the pintail so that it drops through the slots. Unfortunately, the smooth surface of the bottles often make them difficult to rotate, and hence to empty, under real-world working conditions.
After being detached, a pintail may also remain in place within the nose assembly. Subsequent insertion of the pintail of an intact second fastener in preparation for installation of the second fastener may jam the tool. Many conventional tools fail to force pintails out of the nose assembly and out of the nose piston after detachment to make way for the next fastener. Thus, the tool's user is forced to shake the tool until the pintail falls out, or to otherwise spend time and effort to displace the first pintail.
Accordingly, some conventional tools use pressurized air to create a suction effect which draws the detached pintail out of the nose assembly and out of the nose piston. The suction may also be used to hold the next fastener in position between the jaws as the tool is moved to place a portion of the next fastener in the workpiece holes. The suction is created by an air flow which is generated either directly or indirectly by pressurized air that is supplied to the tool through a conventional air hose.
Unfortunately, known tools do not provide an easily operated, flexible means for the user to selectively enable or disable the suction effect. It is desirable to disable suction when the tool is not in active use but is still connected to the air hose in order to reduce the energy spent pressurizing the air hose. It is also desirable to disable the suction, thereby saving energy, if the particular pintails being used do not tend to stick in the particular nose assembly being used but rather slide out easily without suction or substantial user effort.
Some known tools contain only automatic means for disabling the suction effect. These automatic means typically depend on the position of the nose piston relative to the rest of the tool and thus fail to provide users with flexible control over the suction. Other tools contain valves which permit users to enable or disable suction by repeated rotations of a screw, a T-shaped valve handle, or the like. Many such valves are inconvenient because they require a screwdriver or wrench for operation. Moreover, even if such valves are operated solely by hand, they require users to spend too much time and effort performing the necessary repeated rotational movements.
An additional drawback of many conventional installation tools is the difficulty a user faces in properly positioning the tool. A variety of factors typically contribute to make tool positioning difficult. Tool weight is certainly a factor, as the tools commonly weigh from about eight to about 15 pounds. However, other factors are also important. For instance, the tools are often attached to a pressurized air hose by a rigid connector which is fixed in position relative to the rest of the tool. Positioning such a tool requires lifting an extra section of the air hose whenever the tool is not oriented with the air hose connector pointing directly downward.
In addition, the tool handle is typically positioned substantially at a right angle to the nose piston. Users typically hold both the nose piston and their forearms substantially perpendicular to the workpieces. In this position, a conventional tool with a perpendicularly-mounted handle imposes increased stresses on the user's wrist relative to a wrist which is positioned at a more natural angle.
Another drawback of many conventional tools is that they are configured such that the nose assembly and the tool's handle both rest near or on the floor when the tool is set down. The user must "scoop" the tool up by sliding the fingers of one hand along the floor, or even against the floor, until they are under the handle. Repeated scooping movements may result in scraped hands and fingers. In addition, the nose assembly may collect dirt, metal shavings, or other contaminants as a result of being repeatedly placed against the floor of the work area. Contaminated nose assemblies often require a time-consuming cleaning operation before they will operate effectively.
Thus, it would be an advancement in the art to provide a pintail fastener installation tool which provides an easily-operated and flexible suction for removing pintails from the nose assembly after they are detached from fasteners.
It would also be an advancement in the art to provide such a tool which collects the detached pintails in an easily-emptied container rather than allowing them to hit the user or the work area floor.
It would be a further advancement to provide such a tool which facilitates proper positioning of the tool by reducing the stresses imposed on a user.
It would be an additional advancement to provide such a tool which reduces the risk of nose assembly contamination by holding the nose assembly above the work area floor when the tool is set down.
Such an installation tool is disclosed and claimed herein.